/*
 * Copyright 2002-2007 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.context;

/**
 * #Comment#:提供了start()和stop()两个方法,主要用于控制异步处理过程。在具体使用中，
 * 该接口同步被ApplicationContext类和Bean实现
 * ，ApplicationContext会将start/stop的消息传递给容器中所有实现该接口的bean，以达到管理和控制JMX、任务调度等目的。
 * <p>
 * 定义start/stop生命周期控制方法的的接口。典型的应用是用来控制异步处理处理。<br/>
 * Interface defining methods for start/stop lifecycle control. The typical use
 * case for this is to control asynchronous processing.
 * 
 * <p>
 * Can be implemented by both components (typically a Spring bean defined in a
 * Spring {@link org.springframework.beans.factory.BeanFactory}) and containers
 * (typically a Spring {@link ApplicationContext}). Containers will propagate
 * start/stop signals to all components that apply.
 * 
 * <p>
 * Can be used for direct invocations or for management operations via JMX. In
 * the latter case, the {@link org.springframework.jmx.export.MBeanExporter}
 * will typically be defined with an
 * {@link org.springframework.jmx.export.assembler.InterfaceBasedMBeanInfoAssembler}
 * , restricting the visibility of activity-controlled components to the
 * Lifecycle interface.
 * 
 * @author Juergen Hoeller
 * @since 2.0
 * @see ConfigurableApplicationContext
 * @see org.springframework.jms.listener.AbstractMessageListenerContainer
 * @see org.springframework.scheduling.quartz.SchedulerFactoryBean
 */
public interface Lifecycle {

	/**
	 * Start this component. Should not throw an exception if the component is
	 * already running.
	 * <p>
	 * In the case of a container, this will propagate the start signal to all
	 * components that apply.
	 */
	void start();

	/**
	 * Stop this component. Should not throw an exception if the component isn't
	 * started yet.
	 * <p>
	 * In the case of a container, this will propagate the stop signal to all
	 * components that apply.
	 */
	void stop();

	/**
	 * Check whether this component is currently running.
	 * <p>
	 * In the case of a container, this will return <code>true</code> only if
	 * <i>all</i> components that apply are currently running.
	 * 
	 * @return whether the component is currently running
	 */
	boolean isRunning();

}
